diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 8beb2bc..b4e7301 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -261,7 +261,7 @@
 	}
 #endif
 
-	memset(cpu_evtchn_mask(0), ~0, sizeof(cpu_evtchn_mask(0)));
+	memset(cpu_evtchn_mask(0), ~0, sizeof(struct cpu_evtchn_s));
 }
 
 static inline void clear_evtchn(int port)